PVer4: Add UMA metrics for time taken to: load DB, do prefix check,

components/safe_browsing_db/v4_database.h

Index: components/safe_browsing_db/v4_database.h
diff --git a/components/safe_browsing_db/v4_database.h b/components/safe_browsing_db/v4_database.h
index 9c2e40541efb72fb0f25c5265c4eb43562717200..8fc5c167daa9e27e4438c103eab21be782a2c0cd 100644
--- a/components/safe_browsing_db/v4_database.h
+++ b/components/safe_browsing_db/v4_database.h
@@ -164,7 +164,8 @@ class V4Database {
       const base::FilePath& base_path,
       const ListInfos& list_infos,
       const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
-      NewDatabaseReadyCallback callback);
+      NewDatabaseReadyCallback callback,
+      const base::TimeTicks before);

[Nathan Parker, 2016/10/22 00:24:55]

create_start_time, like the .cc

[vakh (use Gerrit instead), 2016/10/22 01:34:34]

Done.

 
   // Callback called when a new store has been created and is ready to be used.
   // This method updates the store_map_ to point to the new store, which causes